A gas sensor having at least one gas-sensitive electrically conductive layer having a surface region which can be brought into contact with a target gas and in which the work function depends on the concentration of the target gas in contact therewith. At least one electrical potential sensor is capacitively coupled to the surface region via an air gap. The surface region is structured by at least one recess in which a flat material element which is connected to the gas-sensitive layer in an electrically conductive manner is arranged, the material of the material element differing from that of the gas-sensitive layer and comprising a metal and/or a metal-containing chemical compound.